This invention relates generally to electric water heaters, and more particularly to electric water heaters for use in livestock water tanks exposed to low temperature extremes.
Livestock require large amounts of water throughout the year. In order to provide livestock with needed water during winter months, exterior livestock watering tanks are seasonally equipped with electric water heaters to prevent the water contained therein from icing over during cold temperatures. These heaters either float in the tank or rest on the bottom of the tank. The power cord extends from the heater and over the side wall of the tank for connection to a power outlet. Because the heater is not fixed in the tank in these prior designs, it is possible for the heater to be thrown from the tank when an animal drags on the power cord.
Commercially available water tanks typically include a drain opening in their side wall so that the tanks can be drained, e.g. for transporting or so it can be refilled with fresh water. It is desirable to have a tank heater in which the power cord extends from the tank through the drain opening so that cord is out of reach of the livestock. However, the size of the drain plug opening varies depending on the manufacturer, and in many instances the drain openings are too small to permit the male plug of the power cord to be inserted through the opening. As a result, there is a need for a tank heater that can be mounted through a variety of sizes of drain plug openings without modifying the drain plug or the water heater.
In response to this problem, U.S. Pat. No. 6,151,448 discloses the use of xe2x80x9csplitxe2x80x9d cord construction. However, this split cord construction requires the use of extra components, and, hence, it is relatively expensive to manufacture. Additionally, if the detachable section of the power cord is damaged or misplaced the heater will be rendering inoperable.
According to certain aspects of an embodiment of the present invention, an electric heater for mounting through the drain plug opening of a livestock water tank includes an electrical heating element sized for insertion through the drain plug opening, a male plug adapted for connection to a conventional electrical outlet, and a power cord extending between the electrical heating element and the male plug. A drain plug fitting is connected to the proximal end of the heating element and is adapted for insertion into the drain plug opening, the drain plug fitting include a seal adapted to seal the drain plug opening to prevent water leakage though the opening.
According to one embodiment, the heating element may have a maximum outer cross sectional dimension of 0.75 inches or smaller.
The heater may also include a temperature regulating device interconnected between the power cord and the heating element, which is adapted to regulate the heating element so as to maintain the contents of the tank within a preselected temperature range.
According other aspects of an embodiment of the present invention, an electric water heating apparatus for mounting in a water tank having a drain plug opening includes a housing having a back wall which is larger than the drain plug opening and body portion extending from the back wall, the body portion being sized for insertion through the drain plug opening including a threaded portion. An electric heating element extends from the end of the body portion opposite the back wall. The heating element is sized for insertion through the drain plug opening and is configured for immersion into the contents of the tank. A power cord has one end mechanically and electrically connected to a male plug. The other end of the power cord extends into the housing is electrically interconnected with the heating element for delivering power thereto. A fastener, such as a nut, threads onto the threaded portion of the housing from inside the tank to secure the heating element within the tank. A seal is provided to seal the drain plug opening around the housing to prevent leakage therethrough. A temperature regulating device is interconnected between the power cord and the heating element. The temperature regulating device is adapted to regulate the heating element so as to maintain the contents of the tank within a preselected temperature range.
The seal may be an annular washer which is compressed between the water tank side wall and the back wall as the nut is threaded onto the boss.